Mutations in members of the tubby gene family have been associated with retinal degeneration in humans, as well as in mice. Thus, the clinical importance of elucidating the regulation and function of this family of proteins is evident. This study endeavors to accomplish the goal of better understanding the role of members of the Tubby gene family through mapping of modifier loci and the adjunct use of microarray analysis to help more rapidly identify candidate modifier genes within our region of interest. Successful completion of the proposed experiments will identify, respectively, loci capable of modifying the tub/tub or tulp1-/- mutant phenotypes and downstream targets of the Tubby gene family members. It is hypothesized that these experiments will aid in understanding the role of the tubby gene family in retinal development and will potentially provide new treatment modalities for human patients suffering certain forms of retinal degeneration.